Onan 5500 problems please help!

[53block]

Hello brethren, I have come to y'all With another problem! I have a 2000 fleetwood bounder and original generator. I'm the 2nd owner. The generator hour guage is broken and stuck on 1100 so no telling how many hrs are really on it. I just spoke to a Onan 5500 owner at a Cookoff this weekend and he has 15000 hrs on his and he said it runs his whole coach without any lick of trouble. As a very experienced DIY'er I'm looking for suggestions on what to try to fix my problem. Here are some of my observations. BTW it failed big time this weekend at a Cookoff big time. We were miserable
Observations
My generator cuts off under moderate load and temperature
Only one a/c will shut it off.
I changed the oil from 10w40 back to the SAE 30 Oman recommended oil, no change. I know that's a crock of malarchy because oil once it gets to 200 degrees + is all the same thickness regardless of what the label says.
Sorry, rant over! Took off the fuel line to a check for fuel starvation, cranked it, plenty of fuel skeetin out. The exhaust volume is weak compared to my neighbors volume on his. This opinion is based on my small block chevy with nitrous tuning opinion. Also his exhaust is warm, mine is super Hott.
Removed the plugs and they look clean. The porcelain is white and there is no evidence of detonation, oil burning or ovefueling. If anything it might be a touch lean IMO. When the generator turns off I checked the oil and it had some smoke or fumes comit out the crankcase which could be from a little blow by or crankcase windage. Oil is not foaming and is at the proper level. The carb is set at 0 elevation but when I move it to 10000 elevation it doesn't make any difference in performance and it should technically lean it out and Make it surge at zero elevation. Could the circuit board be failing because it is super Hott to the touch. Oil sensor failing? Carb problems? Just looking for suggestions to try because if we can't fix it, we are just gonna have to buy another one. We have the cash available no problem to put it in the shop and switch out to a new quiet gas 5500 with propane backup, I just hate to spend 5k that we don't have to! I really love this Motorhome because we use it and use it and use it for cookoffs, vacations etc. we don't baby it but do take care of it. It's a peice of equipment to be used and we don't have to worry about the new Motorhome woes of a scratch or crack or something broken. So I want to keep this baby going. The coach only has 15k miles

While I'm at it, my intellitec controller is flipping out every time I turn on either of the fluorescent lights.

[vtbigdog]

From what you say, I would go back and look at the fuel pump again. While you may see fuel coming out you really have no way to test the fuel flow when the generator is under load. A lean condition causes heat which may explain your hot exhaust, unability to lean out the mixture adjusting the set screw (it is already lean), as well as the color of the spark plug.

[Sammie]

With a 13 year old motorhome, I would take a good look at the fuel line that runs from the generator to the fuel tank. The rubber fuel line can start to develop cracking and suck air where it attaches to the fuel tank and then you will experience vapor lock and the generator will stop running.

Hope this helps.
Sammie

[clyon51]

Possible fuel line problem between filter and tank: Get a 3' piece of fuel line, attach to fuel fllter and place in a jug of gas. See how it runs/performs now.

If this generator sat for any period of time, I would put a double or tripple dose of Seafoam in that gas jug and let it run for an hour, then put the load to it. This should clear up a gummed up carb. I do this annually as maintainance.

I would next suspect fuel filter, then fuel pump. At this point you may have $80 into it.

[Keitha]

This might be worth taking it in for repair.

Now if your able. A gallon gas container with a mix of seafoam and gas, a piece of fuel line and run this through. Seafoam is a fuel system cleaner.
Check for leaking gaskets/ loose carburetor hold down bolts.
R&R carburetor and get it cleaned w/ an ultrasonic cleaner.
Adjust valves.
Maybe a compression test, and or a leak down test.
Condition of air filter?

Keith

[abarkl]

It's the fuel pump. Just replaced mine on a 2001 5500 and no more symptoms just as you described.

[UFO Pilot]

My 5500 had 2 fuel filters, 1 at the fuel pump and 1 at the carb. If yours is the same, the one at the carb is behind the air filter box.

[53block]

Originally Posted by abarkl

It's the fuel pump. Just replaced mine on a 2001 5500 and no more symptoms just as you described.

Tha is for all the replies everyone.
I will get the parts ordered tomorrow. New fuel pump and filer(s) and fuel line. I will borrow a compression tester from my uncle and see what it's doing. Even though 8:1 compression is only about 120 psi, it should help a little. When we used to build engines for their pro mod cars, the tell tell was always in the leakdown test but the piston has to be on the tdc of the compression stroke and hold that crank angle, with that low of a compression I would think the 100 psi applied to the piston would force it down with only 1 other cylinder. I'm gonna give it a go.

Anyone else have any idea why my intellitec load/climate control is freaking out anytime I turn on the fluorescent lights? I read I could be electric noise causing it.

[clyon51]

Yes a bad flouresent fixture can cause this. Just turn one on/off at a time until you find it.

[mgscott4]

I heard that Onan no longer uses 2 fuel filters on the 5500 gen. Only the one attached to the fuel pump is used. They sell you a nipple that screws into the carburetor instead of a second filter.

[Keitha]

In my business, when running a leak down test, actually a blow by test I usually run 30-50 lbs. plenty enough to hear what I'm looking for.
yes the "fancy gauges will give you a % of leakage. For me yes it leaks by or no it doesn't.
It is tough holding an enclosed gen set from turning over.
Keith